Last week's autumn statement was a pretty dreadful day for the Liberal Democrats – only 12 months after Nick Clegg had fought the good fight to protect benefits from inflation, he signed off on a package that allows inflation to eat into the incomes of the poorest for three year in a row. VAT has already risen, tax credits are being shredded and the party's costly fixation with higher personal allowances will not adequately compensate the poor. It is increasingly hard to discern any progressive element to this government on the fiscal front.

On social affairs, by contrast, the coalition's Lib Dem wing is more inclined to flap, as the last seven days have demonstrated, in marked and perhaps deliberate contrast to the week before. Pushing on with gay marriage represented a liberal victory over some, though not all, Conservatives. Mr Clegg has also spoken brave sense on drugs, although his hopes of calling time on a lost war will no more disturb reality than a dream from the opium den. More significantly, he told Theresa May to go "back to the drawing board" on electronic surveillance.

The draft communications bill is sold as an incremental update of surveillance techniques, but in a world where loves, interests and anxieties are all routinely explored online, to entitle the state to keep automated tabs on the pattern of our communications and internet use is to invite a silent spy into every home. It is exactly the sort of thing that the late great Lord Bingham had in mind when he warned that Britons were becoming "the most spied-upon people in the democratic world". Two parliamentary committees, including the prime ministerially appointed intelligence and security committee, have registered concerns of practicality and principle. Freedom-loving Tories have spoken up against, and the Daily Mail has rallied to the ideal that an Englishman's cache is his castle. Mr Clegg is standing important ground here, but it is hardly difficult ground to defend.

The real test of Lib Dem mettle will instead come over secret courts. The party in the country spoke loud and clear at its conference in September, defeating the platform's call for compromise, and resolving that justice in the dark is no justice at all. If that sounds like airy rhetoric, call to mind the gritty detail of cases such as Sami al-Saadi, the Libyan dissident paid £2.2m by Britain this week. His claim is that MI6 played an important part in his rendition to Tripoli, where he was locked up and tortured by the Gaddafi regime, and the size of the settlement does not suggest that this can be lightly dismissed. This is precisely the sort of case that secret courts would keep hidden. Indeed, the proposals were cooked up after Whitehall had raged at previous payouts relating to allegations of British complicity in rendition, and it could even be that Mr al-Saadi – who provocatively points to his unhappy experience of secret justice in Libya – decided to settle because he foresaw that the legislation would pass in time to deny him his day in court.

Expect to hear a good deal about changes round the edges, which were made to the bill in the Lords. David Cameron confirmed this week that the decision as to when to switch off the light in court will now rest with a judge, whereas in the breathtaking original plans the decision was effectively the minister's. Welcome as that change is, it offers little protection – judges traditionally defer to the executive when the security whistle is blown. Other amendments, such as a supposedly equivalent right for individual litigants to demand secrecy (when would they want this?) are an irrelevance. None of the changes touch the heart of the matter – that by allowing one side to rely upon secret evidence which the other cannot challenge, the plan will upset the scales of justice. If the Lib Dems truly want to demonstrate that they are still a countervailing force against Tory authoritarianism, then tipping these scales back to balance would be the place to start.